Flat gasket

ABSTRACT

Flat gasket for sealing a sealing gap between sealing surfaces of machine components which are pressable against the flat gasket, the flat gasket having a gasket plate formed by several sheet metal layers and provided with at least one elastomeric sealing element in an area serving to seal a sealing gap area in which the component sealing surfaces lead to a locally varying sealing surface pressure at the flat gasket, the sealing element being arranged on a first one of the sheet metal layers and, in the mounted state of the flat gasket, extending through a cutout in a second sheet metal layer forming a first one of the main surfaces of the gasket plate; in order that the sealing element can already be applied by the gasket manufacturer, but, nevertheless, is protected against damage in the course of assembly of the machine components, the gasket is so designed that the sealing element is in the form of a sealing element formed from a material which is applied to the first sheet metal layer and is curable in situ, and the sealing element is pressed through the cutout of the second sheet metal layer only when clamping the gasket between the component sealing surfaces.

[0001] The invention relates to a flat gasket for sealing a sealing gapbetween sealing surfaces of machine components which can be pressedagainst the flat gasket. The flat gasket has a gasket plate comprisingat least two sheet metal layers arranged on one another.

[0002] The sheet metal layers forming the two main surfaces of thegasket plate of such flat gaskets are usually provided with beads atparticularly critical places with respect to the sealing function wherean increased sealing surface pressure is to be generated between theflat gasket and the sealing surfaces of the machine components which areto be sealed off from one another. However, such beads have proveninadequate at places where the machine component sealing surfaces,between which the flat gasket is clamped, are uneven, for example, havesteps, as is the case when with a machine component sealing surfaceresting against the flat gasket there are several, for example, two,sealing surface areas which are formed by several separate machinecomponents resting against one another in the area of this step, i.e.,forming a joint—at such joints manufacturing and/or assembly tolerancescan result in a step in the said sealing surface.

[0003] This problem typically occurs with flat gaskets in the form ofcylinder head gaskets for reciprocating internal combustion engines withan, in particular, multipart chain case which is likewise to be sealedoff by the cylinder head gasket, because in this case the two machinecomponent sealing surfaces between which the cylinder head gasket isclamped, are formed, on the one hand, by the cylinder head and a chaincase top part, and, on the other hand, by the engine block or crankcaseand a chain case bottom part—with such an engine construction there isboth a joint between the cylinder head and the chain case top part and ajoint between the engine block and the chain case bottom part. However,the top part of the chain case can also be formed by the cylinder headso that there is no separate chain case top part, or the bottom part ofthe chain case can be formed by the engine block so that there is noseparate chain case bottom part. Nevertheless, a joint still results inthe bottom or top one of the sealing surfaces between which the cylinderhead gasket is clamped.

[0004] Several solutions to the above-described problem caused by jointsare to be found in the prior art:

[0005] EP-A-0 059 777 discloses a single-layer, metallic flat gasket fora multipart gear housing with a housing top part and a housing bottompart, between which the flat gasket is clamped. The housing top partitself is made up of several parts so that joints result in the sealingsurface of the housing top part which has to be pressed against the flatgasket, and these can lead to steps in an area of the sealing surface.For this reason, the flat gasket has an elongate, slot-shaped opening,which extends over all these joints when the gasket is installed andinto which a strand-shaped, elastomeric sealing element is placed, whichprojects on both sides above the two main surfaces of the flat gasketand is made as a prefabricated insert.

[0006] Solutions to the above-described problem for cylinder headgaskets which also serve to seal off a chain case are also to be foundin the prior art:

[0007] DE-C-43 37 758 shows a multilayer, metallic cylinder head gasketin which prefabricated elastomeric sealing elements are inserted, morespecifically, at places on the cylinder head gasket which each lie overa joint between engine block and chain case. In a first, four-layeredembodiment of this cylinder head gasket, each of the sealing elementshas an approximately T-shaped cross section with a sealing portion and ahead portion which is thickened in relation to the latter and serves tofix the sealing element in the cylinder head gasket. For this purpose,the two center layers have for each sealing element rectangular,window-like openings lying above one another for receiving the headportion of the respective sealing element, while the one cover or outerlayer is closed in the area of the sealing elements and the other coverlayer has for each sealing element a rectangular, window-like openingthrough which the sealing portion of the sealing element engages andwhich is smaller than the openings of the center layers and the crosssection of the head portion. In the unpressed state of the cylinder headgasket, the sealing portions of the sealing elements already project toa considerable extent beyond the cover layer provided with the openings.In a second embodiment of this known cylinder head gasket, which hasthree layers, all three layers have at the locations of the sealingelements rectangular, window-like openings lying above one another, andthe openings of the center layer are somewhat larger than the openingsof the cover layers, which are of the same size, so that the sealingelements are held securely against displacements between the coverlayers with central areas of increased diameter. In this secondembodiment, too, the sealing elements already project beyond the onemain surface of the gasket in the unpressed state of the cylinder headgasket.

[0008] Finally, EP-B-0 701 051 discloses a multilayer, metallic cylinderhead gasket which also serves to seal off the chain case. The gasketplate of this cylinder head gasket has a relatively thick center layerand two relatively thin outer layers, which are each provided with aso-called half bead, which extends around the chain case opening as abead line closed within itself (in contrast to full beads ofapproximately U-shaped cross section a half bead has a cross sectionwhich corresponds to a step or Z pulled more or less flat). Beside eachof the two narrow sides of the chain case opening the center layer has acutout in the form of an elongate, rectangular window, which extendsparallel to the adjacent narrow side of the chain case opening, and aprefabricated, strand-shaped, elastomeric sealing element which isinserted with play in the respective window and projects on both sidesover the two main surfaces of the center layer (already prior toinstallation of the cylinder head gasket, i.e., while it is unpressed).One of the outer layers is closed over the sealing elements, i.e.,continuously, while the other outer layer has a large, approximatelyrectangular window which is larger than the chain case opening andexposes the two sealing elements, i.e., in a plan view of the cylinderhead gasket, the two sealing elements lie within this window. EP-B-0 701051 does not explain how with this known cylinder head gasket the twosealing elements are to be prevented from falling out of the gasketduring handling thereof. Furthermore, this known cylinder head gasket isonly able to partly solve the problem explained at the outset when inthe machine component sealing surfaces to be pressed against thecylinder head gasket, there are joints on both sides of the cylinderhead gasket because the chain case is comprised of a chain case top partand a chain case bottom part. Moreover, as will be apparent from thefollowing, this known gasket can also lead to problems when on the sideof the outer layer provided with the windows there is a chain case partwhich is inserted from the side during assembly thereof.

[0009] When assembling engines with a chain case comprised of a top partand a bottom part, it has already been attempted to solve the problemset forth at the outset by providing the cylinder head gasket on eitherside of the chain case opening with a relatively small, oval hole whichpasses through all layers of the multilayer metallic cylinder headgasket and into which an initially viscous sealant is injected in thecourse of assembly of the engine, which can be cured to an elastomericmaterial at elevated temperatures, for example, when the engine is firstput into operation. It is, however, obvious that such a procedure whenassembling the engine in series production is unsatisfactory for severalreasons: Today, vehicle manufacturers tend to delegate as many worksteps as possible to their suppliers, and in series production it isalso difficult, but at least time-consuming to always inject the amountof sealant necessary for reliable sealing into the said holes.

[0010] Furthermore, with the flat gaskets in question there is oftenalso a further problem which can be illustrated well with reference toan engine with a multipart chain case: If, for example, the chain casetop part is guided parallel to the plane of the sealing gap which is tobe sealed by the cylinder head gasket, there is the risk when assemblingthe chain case top part that an elastomeric sealing element projectingabove the surface contour of the gasket plate will be cut off. The sameapplies accordingly to a chain case bottom part guided parallel to theplane of the sealing gap or to constructions with only one separatechain case part which is guided parallel to the plane of the sealinggap.

[0011] The object underlying the invention was to create a flat gasketwith a gasket plate which comprises several sheet metal layers, andwhich is provided with at least one elastomeric sealing element in agasket plate area which serves to seal a sealing gap area betweensealing surfaces of machine components which can be pressed against theflat gasket and in which the component sealing surfaces result in alocally varying sealing surface pressure at the flat gasket, in order toreliably seal the sealing gap also at places where a step may occur in amachine component sealing surface. The flat gasket is to be of such akind that the sealing element is already applied by the gasketmanufacturer and is not subjected to the danger of being damaged or evencut off when assembling the assembly group comprising the machinecomponents and the flat gasket. In particular, the invention is tocreate a cylinder head gasket for an engine with a chain case, whereinthe chain case comprises a chain case top part and/or a chain casebottom part, which contributes or contribute to the formation of thesealing gap to be sealed by the cylinder head gasket.

[0012] This object is accomplished by a flat gasket as defined in claim1, i.e., by a flat gasket for sealing a sealing gap between sealingsurfaces of machine components which are pressable against the flatgasket, the flat gasket comprising a gasket plate formed by at least twosheet metal layers, the gasket plate being provided with at least oneelastomeric sealing element in a gasket plate area serving to seal asealing gap area in which the component sealing surfaces lead to alocally varying sealing surface pressure at the flat gasket, the sealingelement being arranged on a first one of the sheet metal layers and, inthe mounted state of the flat gasket, extending through a cutout in thesecond sheet metal layer forming a first one of the main surfaces of thegasket plate as far as the component sealing surface adjacent to thesecond sheet metal layer, and the surface contour of the second sheetmetal layer defining at this first main surface of the gasket plate aplane of the maximum level of the said surface contour parallel to theplane of the gasket plate in the unmounted, unpressed state of thegasket. Such a flat gasket according to the invention exhibits thecombination of the following features:

[0013] (a) the sealing element is in the form of a sealing elementformed from a material which is applied to the first sheet metal layerand is curable in situ;

[0014] (b) the material of the sealing element is initially capable ofundergoing plastic deformation at least at operating temperature(possibly also below it) of the machine components and the flat gasket;and

[0015] (c) the gasket plate and the sealing element are so designed thatin the unmounted, unpressed state of the flat gasket, the sealingelement extends at the most as far as the said plane of the maximumlevel.

[0016] With a flat gasket wherein the second sheet metal layer formingone of the main surfaces of the gasket plate has in the area or in thevicinity of the sealing element (in a plan view of the flat gasket) forexample, a bead which forms in the said main surface of the gasket platean outwardly projecting step or elevation, the said plane of the maximumlevel is that plane which extends parallel to the plane of the gasketplate and lies on the bead. The same applies accordingly to otherelevations of the surface contour of the aforementioned first mainsurface of the gasket plate in the area or in the vicinity of thesealing element. In a flat gasket according to the invention, thesealing element is thus protected from the danger of being severed, forexample, in the course of assembly of the chain case top part and/orchain case bottom part because the sealing element, before the flatgasket is clamped in the sealing gap between the machine components (forexample, by tightening the cylinder head screws), does in no way projectbeyond the said plane of the maximum level, and, consequently, isprotected by other gasket parts or by the surface contour of the gasketagainst damage.

[0017] Furthermore, the sealing element can already be mounted by thegasket manufacturer so that when assembling the machine components, nofurther work need be carried out on the flat gasket itself.

[0018] When in the foregoing mention has been made of the fact that thematerial of the sealing element is to be initially capable of undergoingplastic deformation at least at the operating temperature of the machinecomponents and the flat gasket, the following is to be understood bythis: The initially applied, not yet cured material from which thesealing element is formed, should at least also be capable of undergoingplastic deformation and to a certain extent at least until the flatgasket is clamped between the machine components to be sealed off fromone another. The material from which the sealing element is formed canalready be partially wetted prior to installation of the gasket, inorder to bring about a certain dimensional stability, without thesealing element thereby losing all plasticity or all ability to flow.The material of the sealing element can then cure fully, for example, atoperating temperatures (e.g. of the engine) or at lower temperatureswhich are elevated with respect to room temperature to the extent thatit then only exhibits elastic, but no longer any plastic properties.

[0019] The underlying principle of the invention enables the gasketplate and the sealing element to be so designed that a sealing area ofthe sealing element, which is sealingly effective when the gasket ismounted, is only pressed through the cutout of the second sheet metallayer and pressed against the component sealing surface adjacent to thissecond sheet metal layer by clamping the flat gasket between the machinecomponents. With the gasket not yet mounted, i.e., unpressed, thesealing element can either not yet project into the cutout of the secondsheet metal layer at all or can engage in this cutout or can even engagethrough this cutout, but at least not project out of this cutout to theextent that the said sealing area of the sealing element projects beyondthe above-defined plane of the maximum level of the unpressed gasket.

[0020] If a flat gasket according to the invention is provided for aninstallation situation in which the machine component sealing surfaceslying on both sides of the flat gasket both have steps or similarunevennesses which are difficult to seal off, it is recommended to sodesign the gasket that also the first sheet metal layer has in the areaof the sealing element a further cutout for entry of the sealing elementmaterial into this cutout. Firstly, this further cutout can serve toimprove the anchoring of the sealing element on the first sheet metallayer. Secondly, or alternatively, the sealing element material can bepressed through this further cutout and pressed against the componentsealing surface adjacent to the first sheet metal layer by clamping thegasket in the sealing gap which is to be sealed. If a flat gasketaccording to the invention requires three or more sheet metal layers, asis often the case with cylinder head gaskets, the principle underlyingthe present invention opens up several possibilities also in the eventthat the component sealing surfaces lying on both sides of the flatgasket both have steps or unevennesses which are similarly difficult toseal: One could provide the first sheet metal layer on both sidesthereof with sealing elements which pass through cutouts in the outer orcover layers of the gasket when clamping the gasket. Alternatively, inan embodiment in which also the first sheet metal layer has in the areaof the sealing element a further cutout for entry of the sealing elementmaterial into this cutout, the gasket plate can have on the side of thefirst sheet metal layer located opposite the second sheet metal layer athird sheet metal layer which is provided over the cutout of the firstsheet metal layer with a further cutout for entry and passage of thesealing element material into and through this further cutout.

[0021] As will be apparent from the above, the sealing problem withengines having at least one separate chain case part as explained abovecan be solved with a flat gasket according to the invention, morespecifically, with a gasket as defined in claim 8, wherein the cutout ofthe second sheet metal layer is designed and arranged so as to bridgethe joint between a first chain case part and the engine componentadjacent thereto (the first chain case part can be a chain case top partor a chain case bottom part and the adjacent engine component can be thecylinder head and the engine block, respectively). If the joint problemexplained above exists on both sides of the cylinder head gasket, acylinder head gasket according to the invention is then so designed thatthe above-mentioned further cutout (in the first or third sheet metallayer) is designed and arranged so as to bridge the joint between thesecond chain case part and the engine component adjacent to thereto.

[0022] In preferred embodiments of a cylinder head gasket according tothe invention for engines with a chain case, the second sheet metallayer is provided in the area or in the immediate vicinity of its cutoutwith a bead (full bead, but preferably half bead), which forms on themain surface of the gasket plate a projection rising above the cutout ofthe second sheet metal layer. With such a naturally elasticallydeformable bead, sealing can be effected with sufficient reliability allaround the chain case opening where the engine component sealingsurfaces do not have any steps. In addition, or, as an alternative, thebead can protect the sealing element or sealing elements against damage.

[0023] The invention will be explained in further detail hereinbelowwith reference to a preferred embodiment of a cylinder head gasketaccording to the invention, which is shown in the appended drawings. Inthe drawings:

[0024]FIG. 1 is a plan view of part of the cylinder head gasket, whichcomprises two combustion chamber openings and a chain case opening ofthe gasket;

[0025] FIGS. 2-4 are sections along lines 2-2, 3-3 and 4-4 in FIG. 1;

[0026]FIG. 5 is the area “A” indicated in FIG. 1 on a larger scale; and

[0027]FIG. 6 is a section along line 6-6 in FIG. 5, with parts of anengine block, a cylinder head, a chain case top part and a chain casebottom part of an engine belonging to the gasket also indicated in FIG.6.

[0028] The cylinder head gasket shown partially in FIG. 1 has a gasketplate generally designated 10, in which a plurality of openings passingthrough the gasket plate are formed, for example, combustion chamberopenings 12, screw holes 14 for passage of cylinder head screws, andwater and oil holes 16 and 18, respectively. The cylinder head gasketalso contains a chain case opening 20, around which sealing surfaces ofa chain case top part and an adjacent cylinder head as well as a chaincase bottom part and an adjacent engine block are to be sealed off fromone another by the cylinder head gasket.

[0029] As will be apparent, for example, from FIG. 2, the gasket plate10 is three-layered and comprises two outer or cover layers 22 and 24consisting of steel sheets having elastic properties and being providedwith beads, and a metallic center layer 26 folded back upon itselfaround the combustion chamber openings 12 and, therefore, usuallyreferred to as flanged sheet layer. At several locations adjacent to theedge of the gasket plate 10, the three sheet metal layers 22, 24 and 26are joined to one another by hollow rivets 28, as shown in greaterdetail in FIG. 3.

[0030] Around the chain case opening 20 there extends in the outer layer22 and the outer layer 24, in each case, a half bead 30 (see also FIG.4), which forms a bead line closed within itself and the crest of whichis designated 30 a.

[0031] The engine components relevant to the present invention areindicated, albeit only area-wise, in FIG. 6, namely a cylinder head 34,an engine block 36, a chain case top part 38 and a chain case bottompart 40. The joints at which the cylinder head and the chain case toppart or the engine block and the chain case bottom part border on oneanother (butt joints) are designated 42, because in the illustratedembodiment the two joints or interfaces lie exactly above one another,and, for this reason, they are only indicated by a single dot-and-dashline in FIG. 5.

[0032] Whereas in the ideal case, which is difficult to bring about inpractical terms, cylinder head and chain case top part or engine blockand chain case bottom part form continuous, flat sealing surfaces,between which the cylinder head gasket is clamped, manufacturing andassembly tolerances often lead to the sealing surfaces designated 51 and52 in FIG. 6 forming a small step at the joints 42. The step in thesealing surface 52 is, as a rule, significantly larger or higher than astep which may be present in the sealing surface 51, as assembly of thechain case top part 38 is often carried out on positioning pins and sovery precisely. The sealing surface 52 in the area of the chain casebottom part 40 can lie lower than in the area of the engine block 36 by0.2±0.2 mm, i.e., up to 0.4 mm, and, therefore, in accordance with theinvention, the height of the “step” formed by the half bead 30 of thelower outer layer 24 is chosen significantly larger (e.g. 0.45 mm) thanthe height of the “step” (e.g. 0.25 mm) formed by the half bead 30 ofthe upper outer layer 22.

[0033] The subject matter of the present invention are two essentiallystrand-shaped sealing elements 50 which are arranged on both sides ofthe chain case opening 20, more specifically, beside the narrow sides ofthe chain case opening, and which - in a plan view of the gasket—liebelow and between the half beads 30 or bead crests 30 a. In accordancewith the invention, to produce the sealing elements 50, two strandsconsisting of an initially pasty sealing material and corresponding intheir length to the length of the sealing elements 50 are applied to thesurface of the center layer 26 on the engine block side. The sealingmaterial can be made to solidify, in particular, by heating, so thatinitially it has not only elastic but also plastic properties and thenonly elastic properties. As will be apparent from FIG. 6 in conjunctionwith FIGS. 1 and 5, the lower outer layer 24 has under each sealingelement 50 a window-like cutout 54 whose shape corresponds to that of anelongate hole or a long, narrow rectangle, which extends in thelongitudinal direction of the adjacent sealing element 50. Furthermore,the center layer 26 and the upper outer layer 22 have over each sealingelement 50 a further cutout 56 and 58, respectively, and these twosimilarly window-like cutouts preferably lie congruently above oneanother and have the shape of a significantly shorter elongate hole (incomparison with cutout 54). In a preferred embodiment, the cutouts 54,56 and 58 have the following dimensions:

[0034] cutout 54: 3×23 mm

[0035] cutouts 56, 58: 3×5 mm.

[0036] In accordance with the invention, the height of the sealingelements 50 is several times greater (vertical dimension in accordancewith FIG. 6) than the thickness of the outer layers 22 and 24—in apreferred embodiment the height of the sealing elements 50 is from 0.7to 0.9 mm, while the thickness of the sheet metal of the outer layers 22and 24 is from 0.20 to 0.25 mm.

[0037] When applying the sealing material later forming the sealingelements 50 to the center layer 26, the sealing material can enter thecutout 56 of the center layer, as indicated in FIG. 6. In preferredembodiments of the invention, however, when the gasket is unpressed, thesealing elements 50 do not yet engage in the cutouts 54 and 58 since inthese embodiments at least the layers 24 and 26 of the gasket plate 10are spaced from one another so long as the gasket is not clamped, i.e.,not yet pressed. In accordance with the invention, it is only wheninstalling the gasket and clamping the gasket between the machinecomponent sealing surfaces that the material of the sealing elements 50enters the cutouts 54 and 58 and passes through these cutouts so that itprojects over the two main surfaces of the gasket plate 10 and ispressed against the sealing surfaces 51 and 52, more specifically,precisely in the area of the joints 42. The sealing material forms onthe outer side of the gasket plate over the cutout 54 an elongate,elastomeric rib, which is pressed against the sealing surface 52,whereas owing to the slight unevennesses of the sealing surface 51 onthe upper side (in accordance with FIG. 6) of the gasket, a shortelastomeric area of the sealing elements 50 exiting from the cutout 58is sufficient for reliable sealing.

[0038] When manufacturing the flat gasket, it is readily possible, inorder to produce the sealing elements 50, to apply strands of sealingmaterial to the center layer 26 and, more particularly, in such acontrolled way with respect to the length, width and volume of thesestrands as to exactly obtain the desired sealing elements 50. Of course,the strands of sealing material are applied to the sheet metal layer 26before the layers 22, 24, 26 are put together to form the gasket plate10.

[0039] For the sake of completion, mention is made of the fact that theplane of the maximum level as defined above is drawn as a dot-dash-line100 in FIG. 4. In the illustrated embodiment this plane of the maximumlevel extends parallel to the plane of the gasket plate 10 as atangential plane to the bead crest 30 a of the outer layer 24.

What is claimed is:
 1. Flat gasket for sealing a sealing gap betweensealing surfaces of machine components, said sealing surfaces beingpressable against said flat gasket, said flat gasket comprising a gasketplate formed by at least two sheet metal layers, said gasket plate beingprovided with at least one elastomeric sealing element in a gasket platearea serving to seal a sealing gap area in which the component sealingsurfaces lead to a locally varying sealing surface pressure at the flatgasket, said sealing element being arranged on a first one of the sheetmetal layers and, in the mounted state of the flat gasket, extendingthrough a cutout in a second sheet metal layer forming a first one ofthe main surfaces of the gasket plate as far as the component sealingsurface adjacent to the second sheet metal layer, and the surfacecontour of the second sheet metal layer defining at this first mainsurface of the gasket plate a plane of the maximum level of said surfacecontour parallel to the plane of the gasket plate in the unmounted,unpressed state of the flat gasket, characterized by the combination ofthe following features: (a) the sealing element is in the form of asealing element formed from a material which is applied to the firstsheet metal layer and is curable in situ; (b) the material of thesealing element is initially capable of undergoing plastic deformationat least at operating temperature of the machine components and the flatgasket; (c) the gasket plate and the sealing element are so designedthat in the unmounted, unpressed state of the flat gasket, the sealingelement extends at the most as far as said plane of the maximum level.2. Flat gasket as defined in claim 1 , wherein the gasket plate and thesealing element are so designed that a sealing portion of the sealingelement is pressable through the cutout of the second sheet metal layerand pressable against the component sealing surface adjacent to thesecond sheet metal layer by clamping the flat gasket between the machinecomponents.
 3. Flat gasket as defined in claim 1 , wherein in theunpressed state of the flat gasket, the sealing element does not engagein the cutout of the second sheet metal layer.
 4. Flat gasket as definedin claim 1 , wherein the material of the sealing element is curable atelevated temperatures with respect to room temperature.
 5. Flat gasketas defined in claim 4 , wherein the material of the sealing element isnot yet cured so long as the flat gasket is not yet mounted.
 6. Flatgasket as defined in claim 1 , wherein also the first sheet metal layerhas in the area of the sealing element a further cutout for entry of thesealing element material into this cutout.
 7. Flat gasket as defined inclaim 6 , wherein the gasket plate has on the side of the first sheetmetal layer located opposite the second sheet metal layer a third sheetmetal layer having over the cutout of the first sheet metal layer afurther cutout for entry and passage of the sealing element materialinto and through this further cutout.
 8. Flat gasket as defined in claim1 , the machine components being a cylinder head, an engine block, achain case top part adjacent to the cylinder head and/or a chain casebottom part adjacent to the engine block, one component sealing surfacebeing formed by the cylinder head and possibly the chain case top part,and the other component sealing surface by the engine block and possiblythe chain case bottom part, and the flat gasket being designed as acylinder head gasket with a chain case sealing area, wherein the cutoutof the second sheet metal layer is designed and arranged so as to bridgethe joint between a first chain case part and the engine componentadjacent thereto.
 9. Flat gasket as defined in claims 8 and 6, whereinthe further cutout is designed and arranged so as to bridge the jointbetween the second chain case part and the engine component adjacentthereto.
 10. Flat gasket as defined in claims 8 and 7, wherein thefurther cutout is designed and arranged so as to bridge the jointbetween the second chain case part and the engine component adjacentthereto.
 11. Flat gasket as defined in claim 1 , wherein the sealingelement is in the form of an elongate strand of elastomeric materialapplied to the first sheet metal layer, and the cutout of the secondsheet metal layer is designed as an elongate window lying over thisstrand.
 12. Flat gasket as defined in claim 6 , wherein the furthercutout is in the form of an opening lying over the strand.
 13. Flatgasket as defined in claim 7 , wherein the further cutout is in the formof an opening lying over the strand.
 14. Flat gasket as defined in claim12 , wherein the sealing element is in the form of an elongate strand ofelastomeric material applied to the first sheet metal layer, and thecutout of the second sheet metal layer is designed as an elongate windowlying over this strand, and wherein the opening is shorter than thewindow in the longitudinal direction of the strand.
 15. Flat gasket asdefined in claim 13 , wherein the sealing element is in the form of anelongate strand of elastomeric material applied to the first sheet metallayer, and the cutout of the second sheet metal layer is designed as anelongate window lying over this strand, and wherein the opening isshorter than the window in the longitudinal direction of the strand. 16.Flat gasket as defined in claim 1 , wherein the second sheet metal layeris provided in the area of its cutout with a bead which forms on thefirst main surface of the gasket plate a projection rising above thecutout.
 17. Flat gasket as defined in claim 16 , wherein the bead is inthe form of a half bead.
 18. Flat gasket as defined in claim 16 ,wherein the bead forms a bead line closed within itself, which extendsaround a chain case opening of the flat gasket.
 19. Flat gasket asdefined in claim 16 , wherein—in a plan view of the flat gasket—thecrest of the bead lies over the sealing element.